2003 200 HPDI alarm - please help

[Grasscutter]

I get an alarm at low RPM's, but not all the time. It is hard to show the mechanic because it does not do it always. Are there many reasons for this alarm? Is there an electonic tool I can plug in to the motor to see the code for the problem like cars have?

[boats.net]

If you have the Yamaha tach in boat it will have warning lights to see if it's low oilo or overheat warning activated. If it's been awhile since water pump has been replaced then probably need new water pump.

[Grasscutter]

I don't have that kind of gauge. The oil is never low and the motor is not hot to the touch. The spray streams into the water indicating the water pump is working. Any other ideas?